“Investigating the Role of Sarcomere Structure and Bioenergetic Input on Muscle Contraction in Drosophila Using Nonlinear Optical Microscopy“

Abstract

Nonlinear optical microscopy has been shown to be a superior imaging modality compared to fluorescence and electron microscopy. Imaging can be done without prior staining, providing a variety of valuable techniques that can be used to reveal structural and functional information in a biological system. Second harmonic generation is observed in non-centrosymmetric cylindrical molecules such as myosin and can be used to directly visualize muscle structure. It was found through polarization microscopy that the second harmonic signal is generated from the anisotropic bands. Hence, the objective of this research is to investigate dynamic properties of sarcomere structure as well as genetic and bioenergetic inputs in Drosophila Melanogaster muscles. This will be accomplished using three approaches. Recently, it was found that the second harmonic response was affected by the size of the sarcomere. To further characterize the second harmonic properties of muscle, changes in the SHG response as well as polarization dependency on myofibril organization will be investigated at various elongation lengths. These parameters will also be compared in somatic, cardiac and visceral muscles to investigate the changes in SHG response due to changes in myofibril organization. The technique will then be applied to examine changes in second harmonic properties of sarcomere due to presence/absence of various chaperones and co-chaperones responsible for thick filament maintenance. Lastly, THG intensity changes due to activity of mitochondria will be investigated along with its correlation to sarcomere contractions. This imaging technique offers new perspective on the dynamic properties of contraction, and how these properties may be altered in movement disorders.